1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming method.
2. Related Art
Conventionally, there has been known an image forming apparatus that ejects ink droplets to a recording medium such as a sheet by inkjet recording heads.
In this image forming apparatus, ink droplets are ejected to recording medium, the ink droplets ejected to the recording medium are dried and fixed by heating, the recording media are sequentially discharged and stacked on a sheet discharge section. In this image forming apparatus, ink transferring (set off, blocking) are generated between the recording media that overlap each other in the vertical direction when recording media are stacked on the sheet discharge section.
Since the same phenomenon as described above occurs even in offset printing machines in the market, powder containing such as starch is generally sprayed between recording media to avoid set off.
Since there is a lot of moisture contained in ink in a case of an image forming apparatus using inkjet recording heads, as compared to an offset printing machine, set off is apt to occur. For this reason, a powder device, which sprays powder, is used in the image forming apparatus in the similar way as an offset printing machine. However, since much more powder needs to be sprayed than powder used in an offset printing machine, accordingly it is required that the amount of powder be reduced or that powder be made unnecessary.
Further, Japanese Patent Application Laid-Open (JP-A) No. 10-16418 (Patent Document 1) discloses an apparatus that, after printing, cools ink transferred to a recording medium or the vicinity of a portion where ink and ink-curing (hardening) liquid comes into contact with each other by a cooling device and fixes the ink, before, while, or after ink-curing liquid comes into contact with or is applied to an ink-transfer surface of the recording medium.
However, a process for cooling a recording medium by a cooling device is not disclosed in Patent Document 1. For this reason, it is not possible to effectively suppress set off when recording media are stacked on a sheet discharge section. Accordingly, improvement is needed.